expand all images as multipageformat (similar PDF or TIFF)
convert it to webp with wished config
archive it with 7zip (no compression, storemode, only headercompression) with extension cb7
OR
write all webp-images into ONE webP-Anim (with zero timeset) with ext webp

if you support AVIF you can save the comicbook in this with zero timings
maybe you could made a new trend - renamed avif as CBA or CBV